(A) Technical Field
The present invention relates to a latent heat storage tank of a latent heat system wherein a refrigerator is operated using inexpensive night time electric power whereby heat is stored as latent heat in the state of ice or icy liquid by refrigerating the water or liquid enclosed in latent heat containers surrounded with an antifreeze solution cooled by said refrigerator and then using the latent heat for air-conditioning during the day when said ice or icy liquid melts.
(b) Statement of the Prior Art
The following examples are conventionally known as latent heat storage tanks using inexpensive night time electric power.
(1) A latent heat storage tank which is provided with an ice-maker and filled with a circulating anti-freeze solution cooled by a refrigerator to make ice in said ice-maker, for example, disclosed in Japanese Patent Laid-open Publication No. 59-38535.
(2) A latent heat storage tank which contains spherical capsules composed of rigid synthetic resin containing water or solution. And said tank is filled with antifreeze solution. The water or solution in the capsules is cooled by said antifreeze solution by said refrigerator and stores latent heat in the state of ice or icy liquid within said capsules.
(3) A latent heat storage tank having containers made of an expansible heat conductive material positioned with a predetermined distance from each other in which latent heat is stored by refrigerating the water in said containers by antifreeze solution cooled by a refrigerator, for example, disclosed in Japanese Patent Laid-open Publication No. 63-19126.
According to said conventional art (1) the materials used in the ice-maker must be strong because the antifreeze solution is circulated within said ice-maker and the thickness of said ice-maker must be great enough to withstand the internal pressure caused by the antifreeze solution. If a small part of said ice-maker would be bent or blocked, then the antifreeze solution will not flow, and consequently, the material used for the ice-maker should be sufficiently rigid and thick. In addition, the ice which forms on the surface of the ice-maker lowers heat conductivity and thereby reduces efficiency.
In the case mentioned above in (2), the anti-freeze solution is circulated outside the capsules. If the capsules are soft, they will be deformed due to the force of gravity and their own buoyancy, causing the spaces between the capsules to be blocked and disrupting the even flow of the antifreeze solution. Since the deformation of the capsules can not be allowed, the capsules should be made of a rigid materials and their thickness should be increased even though this results in a decreased rate of heat transfer.
According to the point (3) above, the cost of the production is high and it is necessary to restructure the tank body when using a tank of conventional type, because the containers made of an expansible heat conductive material must be hung or fixed to the tank body.